What happened to Mat Mustard, the lead Vallejo detective in ‘American Nightmare’?

This story was published in partnership with the San Francisco Chronicle. 

VALLEJO, CA — The hit Netflix docuseries “American Nightmare” introduced millions of new viewers to Denise Huskins and Aaron Quinn, two former Vallejo residents who endured a horrific home invasion and kidnapping in 2015 only to be publicly branded liars by the Vallejo Police Department. Months passed before Huskins, who was held for ransom and raped twice, was vindicated as a victim rather than a “Gone Girl” hoaxster.  

But another character takes a starring role in the production: Mat Mustard, the lead detective in the botched case.

In a small interrogation room that becomes a pivotal setting in the series, Mustard sits across a table from Quinn as a camera perched in a corner records. Quinn recounts how, just hours earlier, he was blindfolded and drugged by intruders at the couple’s home on Vallejo’s Mare Island. But the detective isn’t focused on locating Huskins, instead accusing Quinn of killing her and fabricating her disappearance.

“I’m a puzzle-maker. And I put a lot of puzzles together,” Mustard tells Quinn during 18 hours of questioning. “So now I get out my puzzle pieces, and I start figuring out, how do I make it so you look like a monster?”

“I didn’t do anything,” Quinn says at one point.

“Yeah you did,” Mustard replies.

What the show doesn’t reveal is that Mustard — who was never disciplined in the case but rather named “Officer of the Year” by his department months later — has been embroiled in several controversies within the Vallejo force and in investigations he’s handled. He was accused by one colleague of making racist comments, which he denied, and by another of pushing for lower promotion standards so he could be elevated to sergeant.

Mustard, who is still a sworn officer in Vallejo, could not be reached for comment for this story. An automatic reply on his city email said he was out of the office, but did not indicate when he would return. A phone number listed in his name has been disconnected. The Vallejo Police Department did not respond to a request for comment. 

In the past, Mustard has defended his work investigating the kidnapping, which was ultimately linked to a former Marine and Harvard-educated attorney, Matthew Muller, who released Huskins after two days and is now serving a 40-year prison sentence. Muller sent messages to the San Francisco Chronicle after abducting Huskins, first providing a proof-of-life recording and later attacking police for calling his crime a hoax.

In 2016, Mustard filed a written declaration in a lawsuit the now-married couple filed against him and the police department that was later settled for $2.5 million. Mustard stated that “from the inception of the case, my main concern was to locate Ms. Huskins” even though he was “skeptical” of Quinn’s story “because of its outlandish nature.”

Quinn said in a phone interview last week with the Chronicle and the Vallejo Sun that he was frustrated not only that Mustard “derailed the entire investigation,” but was not punished for it. “They made everything worse, and there was no accountability,” Quinn said. “And it’s not just Mustard, but those who enabled him. Why would he ever change if there’s no consequences?”

Mustard has been a Vallejo police officer for more than two decades. The department hired him in 2001, and he became a detective three years later. In 2009, he was elected president of the union representing rank-and-file officers, the Vallejo Police Officers Association. 

In 2012, three years before Huskins was kidnapped, a Solano County forensic pathologist alleged that Mustard pressured her to fit the facts of an investigation to his theory of the case. According to police reports, Mustard was called to a Vallejo hotel room where Michael Daniels had called 911, and where officers had found the body of his girlfriend, Jessica Brastow. A sock with her DNA was in the bathroom garbage can, making Mustard believe Daniels had used it to suffocate her, reports state. Daniels said Brastow had choked while eating.

Dr. Susan Hogan, the forensic pathologist assigned to do the autopsy, didn’t find enough evidence to support Mustard’s theory, she told state investigators who later looked into the matter. Hogan recalled Mustard asking her, “What will it take for you to call this a homicide?” In September 2013, Mustard emailed Solano County prosecutors, suggesting they needed to charge Daniels, writing, “we need to throw it against the wall and see what sticks.”

Daniels was ultimately charged, then acquitted in April 2014. 

It was less than a year later that Mustard investigated the Huskins kidnapping and concluded, along with department leaders, that it was a hoax. As the documentary recounts, the kidnapper or kidnappers — Huskins and Quinn say at least three people entered their home — attempted to call Quinn on his cellphone, which police had set to airplane mode as they tried to elicit a confession.

Investigators later traced the calls to Quinn’s phone to a street in South Lake Tahoe where Muller was holding Huskins. Had police monitored Quinn’s phone and acted quickly, Huskins says in the documentary, they might have rescued her before she was raped a second time.

Mustard said in his 2016 declaration that he had “considered multiple different theories” of the crime, including that “Quinn had killed Ms. Huskins accidentally,” that Huskins had died while the two were “experimenting with drugs,” and that Huskins “wanted to be gone for some reason, and Mr. Quinn was helping her.”

Despite Mustard’s missteps in the case, he remained president of the Vallejo officers’ union, which came under increasing fire as the department attracted scrutiny for a series of controversial killings by officers and a bevy of lawsuits alleging excessive force. In 2020, California Attorney General Xavier Becerra announced a “review and reform agreement” to investigate the department’s practices.

In 2022, a former police captain-turned-whistleblower, John Whitney, testified in a deposition related to his wrongful termination lawsuit he recently settled for nearly $1 million that there was “no accountability inside the police department” and that the union “could kind of delegate policy to how the chief was going to conduct business.” Whitney said some Vallejo officers had bent their badges to commemorate on-duty killings.

According to Whitney, Mustard’s influence as union president extended to the promotional exam for officers seeking to become sergeants. After Mustard failed the written portion of the exam, Whitney said, he pressured then-Chief Andrew Bidou to “put very little significance” on it and made 70% a passing score. Despite the objections of the department’s two captains, “the chief ultimately went with what Mat Mustard wanted,” Whitney testified. 

Mustard was promoted to sergeant in September 2018 and, three months later, was transferred from patrol to lead the investigative division. Within a year, Detective Corporal Jason Scott, who is Black, submitted a written complaint that Mustard “treated him poorly because of his race,” which included Mustard making “a race-based joke and calling him ‘boy,’” according to a city-commissioned investigation completed in 2020 by the law firm Ellis & Makus. 

The investigation found Mustard “discussed” a race-based joke — Mustard denied it had racial connotations — and called Scott “boy” twice, which Mustard didn’t recall. Investigators “did not find Sgt. Mustard’s account as to these issues credible” and concluded that he had “a motive to provide false information” because he faced disciplinary action. It’s not clear if Mustard was ultimately disciplined.

As the COVID-19 pandemic lockdowns began in March 2020, a jury trial was underway in a Vallejo courtroom for Kenneth Weathersby, a man accused of kidnapping and sexually assaulting women on two occasions. It became the last jury trial in California for many months. 

Mustard testified that he was investigating the first attack, which occurred in July 2018, when a similar crime occurred two weeks later. DNA samples from both cases were sent to Kevin Gazlay, a senior criminalist with the California Department of Justice. Gazlay testified that it was “crystal clear” that one sample did not match Weathersby — and noted that he had called Mustard’s personal cell phone to tell him. 

Deputy Public Defender Nick Filloy said the government should have disclosed the exculpatory findings earlier, but that he only learned about them during the trial. Mustard testified that he didn’t “know anything about the phone call” from Gazlay, but the senior criminalist and others at the Justice Department told jurors that Mustard knew of the evidence as far back as summer 2018.

In his closing argument, Filloy quoted Wu-Tang Clan member Ghostface Killah to say Mustard was “dirty like the corner in the bathroom floor.” Weathersby was nonetheless convicted of committing both crimes.

Mustard was replaced as union president in late 2019. The city of Vallejo confirmed Monday that he is still an employee. According to Transparent California, a database of California public employee salaries, Mustard made $129,000 in 2022 after working far less overtime than in previous years. He made $263,000 in 2021 and $274,000 in 2020.

The Chronicle’s Demian Bulwa contributed to this report.